One of the necessary tasks in becoming leaner and improving your industry is to eliminate waste. I like to use a simple approach for measuring waste in manual work to know how good (or bad) the current situation is. To explain my approach I commissioned a few animations. Let me proudly present my approach and my animations, so you can also estimate the efficiency of manual lines when you are on the shop floor.
You are all familiar with the lean concept of waste (muda) as part of the trinity of waste, overburden, and unevenness (muda, mura, muri). You probably know the seven types of waste (although some count eight types or more). Sometimes there is a distinction between avoidable waste (e.g., defects, which should be eliminated) and unavoidable waste (e.g., transport, which should be reduced, but it is hard to produce anything with zero transport).
The Trickiness of Distinguishing Waste from Value Add
Waste is sometimes also contrasted with value add, which is anything that creates value for the customer. Either your people are creating value for the customer or they are not. This sounds simple in theory, but in reality it is sometimes hard to distinguish waste and value add. For example, if you build cars, you need to attach wheels to the cars. The value for the customer is that the car has wheels. Transporting the wheel around is of no value to the customer. Attaching it to the rest of the car is. But then, is the value in screwing in the screws, or merely in tightening them the last quarter turn. Would all those excess turns of the screw be a waste? Can you do it with even less screws? Or could you skip an entire tire?
Even more extreme, if you are a retail or logistics company, you do add value for the customer by providing products to them. But in conventional lean wisdom, all transport and inventory is waste, but clearly the customer is paying for the service.
Overall, you have to think about what your company does that adds value to the customer. At the same time, do not think too hard about it, because then you would start questioning everything. While this is okay in principle, it also has to be practical. If your boss wants you to reduce waste related to attaching wheels to cars, you probably should not suggest flying cars or anti-gravity transportation…
It becomes even more difficult if you do not know the products or process very well – for example, if you are only a visitor to a plant. However, in this case I use a rough estimation to measure the efficiency in manual operations. Let me explain:
Observing Value Add and Waste
I use a simplification to decide if something is waste or value add, and then use a quick-and-dirty estimation to measure what percentage of the time a worker adds value. My simplifications for processes that I am unfamiliar with is that whenever the worker touches the part, it is value add. For example, if the worker adds components to the main part (e.g., during assembly) or removes stuff (e.g., during machining), it is probably (hopefully) value add. Nevertheless, use common sense. If the worker is touching the part but it is obvious that it is waste, then it is waste. Similarly, if the worker is not touching the main part, but nevertheless you believe this to be value add, then it is value add. But for most observations, this “touch-no touch” distinction is good enough for an estimate.
The images below show an example from my animation. In the background you will see a sign that tells you if it is value add or if it is waste, and which type of waste it is. In reality, of course, you do not have such a sign, but for training purposes it helps immensely.
Again, this is a simplification! It is easy to imagine situations where the worker touches the main part, but only to fix a problem or because a component does not fit well. Hence, this method is not perfect and tends to overestimate the value add slightly. On the other hand, you can use this approach even if you are unfamiliar with the process, or if you can observe it only from some distance. Both are common for visitors and tours. So now you can estimate when a worker is adding value and when not.
Measuring Value Add and Waste
This gives the next step: you can count how often you see a worker adding value and how often not. If I see a worker, I wait briefly to understand what he is doing before determining if it is value add or not. Usually, I use a three-second delay. In my head, I count to three, and on “three” I determine if the action at “three” is value add or waste. You can even count the same person repeatedly at different times. To do the actual measurement, I simply count instances of observing value add and instances of observing waste. This counting is a simple list of dashes as shown below.
This brings me to my animation below. This animation is admittedly quite wasteful, but in my next post I will have two more animations with improvements. Look at the animation loop and count to three. At “three,” is the stick figure adding value or doing waste? The sign in the back helps you in this training animation, but of course in reality there would be no such sign. Hence, focus on the person, and after three seconds decide if it is value add or waste. Try to really focus on the timing at “three.” If the worker just added value, but turned around at “three,” then it is no longer adding value. If the worker walked a long distance, but at “three” just started touching the part, then it is adding value, even if he wasted a lot of time beforehand. Count every time you see a value add or a waste at this “three” spot in time.
Now you have a random sample of a few observations, always deciding if it is value add or waste. Of course, more is better. Using these numbers we now can calculate the percentage of the time a worker is adding value (number of observations of value adding divided by total number of observations) or waste (number of observations of waste divided by total number of observations – or simply the remainder to 100%). And, voila, you now know the percentage value add of the manual labor at this line or station.
If you do this measurement for the animation above, then you will get the percentage value add. I did the calculation for you, and it is a measly 17.4% value adding time, with the remaining 82.6% of the time being wasted (24.4% movement waste, 22.2% waiting waste, and 36.2% transport waste). Depending on how many measures you took, you should get numbers somewhere on this magnitude.
These counts can easily be done on the fly during a plant visit, and it may take less than ten minutes to observe a line. If I do it in reality I may have a total of ten to forty observations. You can measure them for the entire plant overall, or separately for different lines or cells.
Keep in mind it is a rough estimate. However, I definitely prefer my own rough estimate over any “official” value add numbers I get, which are most likely “optimized” to look good. I don’t believe 120% value add just like I don’t believe 115% OEEs, and I have seen them a lot 🙁 . In my next post I will show you what values to expect, and also two more very similar but more efficient animations. Now, go out, measure your efficiency, and organize your industry!